U.S. patent application number 09/887978 was filed with the patent office on 2002-04-18 for temporary vascular filter guide wire.
This patent application is currently assigned to C.R. Bard, Inc.. Invention is credited to Gambale, Richard A., Gray, William.
Application Number | 20020045916 09/887978 |
Document ID | / |
Family ID | 23815825 |
Filed Date | 2002-04-18 |
United States Patent
Application |
20020045916 |
Kind Code |
A1 |
Gray, William ; et
al. |
April 18, 2002 |
Temporary vascular filter guide wire
Abstract
A temporary filter is described for use in percutaneous
intravascular procedures for the treatment of diseased blood
vessels, such as angioplasty or stent placement procedures. The
guide wire which is used to direct a catheter (such as a balloon
catheter) to a treatment site contains a deployable filter. The
guide wire is moveable independently of the catheter and can be
used to position the filter at a desired location downstream of the
treatment site. The guide wire includes parts moveable with respect
to each other and the filter is connected to these parts in such a
way that it can be deployed and collapsed by relative movement of
the parts.
Inventors: |
Gray, William; (Mercer
Island, WA) ; Gambale, Richard A.; (Tyngsboro,
MA) |
Correspondence
Address: |
DARBY & DARBY P.C.
805 Third Avenue
New York
NY
10022
US
|
Assignee: |
C.R. Bard, Inc.
|
Family ID: |
23815825 |
Appl. No.: |
09/887978 |
Filed: |
June 22, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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09887978 |
Jun 22, 2001 |
|
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|
09457203 |
Dec 6, 1999 |
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Current U.S.
Class: |
606/200 |
Current CPC
Class: |
Y10T 29/49604 20150115;
A61F 2230/0086 20130101; A61F 2002/016 20130101; A61M 25/09
20130101; A61F 2230/0021 20130101; A61F 2230/0097 20130101; A61F
2/012 20200501; A61F 2230/005 20130101; A61F 2230/0093 20130101;
A61F 2002/018 20130101; A61F 2230/0006 20130101; A61F 2/013
20130101; A61F 2/011 20200501; A61F 2230/0067 20130101; Y10T
29/49801 20150115; A61M 2025/09183 20130101; A61F 2/0108
20200501 |
Class at
Publication: |
606/200 |
International
Class: |
A61M 029/00 |
Claims
What is claimed is:
1. A vascular filter guide wire for directing placement of a
catheter with respect to a blood vessel lesion and filtering
particulate matter dislodged by treatment of said vessel, said
guide wire including: an elongated flexible core wire having a
proximal end and a distal end for insertion and steerage through a
patient's vasculature to a position downstream of said lesion; a
tubular flexible shaft slidably disposed along said core wire, said
shaft including a proximal portion and a distal portion disposed
proximally of said core wire distal end for placement downstream of
said lesion; and a collapsible filter coupled at its proximal end
to said distal portion of said shaft and at its distal end to said
core wire, said filter operable in response to the relative is
displacement between said shaft and said core wire to radially
extend outwardly within said vasculature and trap particulate
matter arising from the treatment of said lesion.
2. A vascular filter guide wire according to claim 1 and further
including: a locking mechanism to maintain said filter in a
deployed position for particulate filtration during lesion
treatment.
3. A vascular filter guide wire according to claim 1 wherein: said
core wire includes a filter housing for confining said filter in a
closed configuration.
4. A vascular filter guide wire according to claim 3 wherein: said
housing is formed in a frusto-conical configuration and axially
disposed on said core wire, said housing including an
oversized-in-diameter mouth opening axially outwardly from said
wire distal end, and a reduced-in-diameter collar radially fixed to
said core wire proximate said distal end.
5. A vascular filter guide wire according to claim 3 wherein said
strainer is formed to collapsibly engage said housing in a closed
state and including: a plurality of radially spaced apart support
struts defining a cage, said struts collapsibly hinged at one end
along a common radial path on said shaft and interconnected through
a woven peripheral mesh; and a biasing element interposed
concentrically between said struts and said shaft to bias said
struts radially outwardly in an open state.
6. A vascular filter guide wire according to claim 5 wherein: said
spaced apart struts are disposed radially equidistant.
7. A vascular filter guide wire according to claim 5 wherein: said
spaced apart struts are disposed in a spiral relationship.
8. A vascular filter guide wire according to claim 5 wherein: said
struts are formed of a high elastic material.
9. A vascular filter guide wire according to claim 5 wherein: said
woven mesh comprises a polymeric material.
10. A vascular filter guide wire according to claim 5 wherein: said
woven mesh density is in the range 40 to 500 micrometers.
11. A vascular filter guide wire according to claim 5 wherein: said
biasing element comprises a quad filar spring.
12. A vascular filter guide wire according to claim 1, further
including a deployment/retraction mechanism including: a removable
base formed with a threaded passage for confining the proximal
portion of said shaft; and a manually rotatable control element,
said control element formed with a threaded hollow shank and
mounted to the proximal end of said wire, said control element
operable to threadably engage said passage and incrementally urge
relative axial displacement between said shaft and said wire to
extend and retract said filter.
13. A vascular filter guide wire according to claim 1 wherein said
filter includes: a cylindrical support cage having a closed distal
end and a flared proximal end, said distal end fixed to the distal
extremity of said shaft, and said proximal end extending axially
and mounted to said core wire distal end; and a continuous woven
mesh having a plurality of longitudinal pleats and disposed within
said support cage for straining particulate matter.
14. A vascular filter guide wire according to claim 13 wherein:
said filter is formed with oppositely disposed cone-shaped ends to
define said front and back halves.
15. A vascular filter guide wire according to claim 14 wherein said
woven mesh is mounted to said cage back half.
16. A vascular filter guide wire according to claim 13 wherein:
said woven mesh comprises a material from the group including
stainless steel and nickel-titanium alloy.
17. A vascular filter guide wire according to claim 13 wherein:
said wire mesh density is in the range 40 to 500 micrometers.
18. A vascular filter guide wire according to claim 1 wherein said
filter includes: a braid comprising a composite metallic/polymeric
material, said material including a plurality of metallic filaments
mounted to said respective shiftable shaft and core wire to define
a support structure and a polymeric mesh interwoven with said
metallic filaments to define a strainer.
19. A vascular filter guide wire according to claim 18 wherein: a
said metallic filaments have respective common proximal and distal
halves; and said polymeric mesh is interwoven in said distal half
of said metallic filaments.
20. A vascular filter guide wire according to claim 18 wherein:
said metallic and polymeric filaments are woven at a ratio of
approximately 1:4.
21. A vascular filter guide wire for directing precision placement
of a catheter with respect to a lesion and filtering particulate
matter dislodged by treatment of said lesion, said guide wire
including: an actuating mechanism; an elongated flexible core wire
having a proximal end attached to said actuating mechanism and a
distal end for insertion and steerage through a patient's
vasculature to a position downstream of said lesion; a tubular
flexible shaft slidably disposed along said core wire, said shaft
including a proximal portion affixed to said actuating mechanism in
movable relation to said wire, and a distal portion disposed
inwardly from the distal end of said core wire for placement
downstream of said lesion; a locking mechanism to maintain said
filter in an extended position during lesion treatment; and a
collapsible filter coupled to said shaft distal portion, said
filter including a collapsible support cage having respective front
and back halves for slidably extending and retracting axially along
said wire, said cage having a first end fixed to the distal
extremity of said shaft, and an opposite end mounted to said core
wire distal end, said strainer further including a continuous woven
mesh disposed within said support cage for straining particulate
matter and operable, in response to manual manipulation of said
actuating mechanism to effect relative displacement between said
shaft and said core wire, to radially extend outwardly within said
vasculature and trap particulate matter arising from the treatment
of said lesion.
22. A catheter system for treating a blood vessel lesion within a
vasculature, said catheter system including: a catheter having a
lesion treatment device; and a vascular filter guide wire for
directing said balloon catheter to said lesion, said guide wire
including a collapsible filter for manual deployment downstream of
said balloon catheter to trap particulate matter arising from the
treatment of said lesion.
23. A catheter system according to claim 22 wherein said vascular
filter guide wire includes: an elongated flexible core wire having
a proximal end and a distal end for insertion and steerage through
a patient's vasculature to a position downstream of said lesion; a
tubular flexible shaft slidably disposed along said core wire, said
shaft including a proximal portion and a distal portion disposed
inwardly from said core wire distal end for placement downstream of
said lesion; and a collapsible filter coupled at one end to said
shaft and at its other end to said core wire, said filter operable
in response to relative displacement between said shaft and said
core wire, to radially extend outwardly within said vasculature and
trap particulate matter arising from the treatment of said
lesion.
24. A method of filtering particulate debris from a vasculature
caused by treatment of a lesion with a lesion treatment device,
said catheter guided to the location of said lesion by a vascular
filter guide wire having a core wire, a slidable shaft, and a
manually collapsible filter mounted on the shaft and deployable
upon relative displacement between said core wire and said shaft,
said method including the steps of: guiding said vascular filter
guide wire through said vasculature along a predetermined path to a
lesion such that said filter is disposed downstream of said lesion;
deploying said filter radially outwardly by shifting said shaft
relative to said core wire; running said catheter over said guide
wire along said predetermined path to position said lesion
treatment device proximate said lesion; treating said lesion
according to a predetermined procedure; maintaining said filter in
a deployed position to trap particulate matter dislodged during
said lesion treatment and prevent said matter from progressing
downstream; withdrawing said catheter from said vasculature;
retracting said filter radially inwardly by shifting said shaft
back to said original position; and removing said guide wire from
said vasculature.
25. A vascular filter for controllably expanding within a blood
vessel to trap particulate matter loosened from a lesion, said
filter responsive to relatively shiftable control elements to
expand and retract, said filter including: a braid comprising a
composite metallic/polymeric material, said material including a
plurality of metallic filaments mounted to said respective
shiftable shaft and core wire to define a support structure, and a
polymeric mesh interwoven with said metallic filaments to define a
strainer.
26. A vascular filter guide wire according to claim 25 wherein:
said metallic filaments have respective common proximal and distal
halves; and said polymeric mesh is interwoven in said distal half
of said metallic filaments.
27. A vascular filter guide wire according to claim 25 wherein:
said metallic and polymeric filaments are woven at a ratio of
approximately 1:4.
28. A method of fabricating a vascular filter, said method
including the steps of: selecting a mandrel having a plurality of
consecutively connected forms; weaving a continuous layer of braid
over said consecutively connected forms; bonding said braid
filaments at spaced apart sections between respective forms;
separating said respective braided forms at said bonded sections;
and removing said forms from said layer of braid.
29. A method of fabricating a vascular filter according to claim 28
wherein said step of weaving includes: forming a layer of braid
over the proximal and distal halves of each form with a composite
metallic/polymeric material to having a pic density sufficient to
strain particulate matter.
30. A method of fabricating a vascular filter according to claim 29
and further including the step of: cutting said polymeric filaments
from said proximal halves of each form; and fusing the ends of said
cut filaments to form a collection cavity around each form.
31. A method of fabricating a vascular filter according to claim 28
wherein after said bonding step, said method further includes the
steps of: installing a filter layer over each form; weaving a
second continuous layer of braid having a plurality of second braid
filaments over said installed filters; and bonding said second
braid filaments at said spaced apart sections.
32. A method of fabricating a vascular filter according to claim 28
wherein said forms are molded from a dissolvable material, said
step of removing including: dissolving said forms by an appropriate
solvent.
Description
FIELD OF THE INVENTION
[0001] The invention relates to vascular filters intended to
capture embolic particles, by means of filtration, that may arise
from the treatment of diseased blood vessels.
BACKGROUND OF THE INVENTION
[0002] Percutaneous intravascular treatment of diseased blood
vessels, such as angioplasty or stent placement procedures, may
result in the dislodgment of loose plaque or thrombus which then
migrate downstream. Since any such particles may become lodged in
other vessels, effectively preventing blood from passing into the
organ which that vessel supplies, and potentially causing serious
end-organ damage which may be difficult or impossible to reverse,
effective avoidance of this complication is extremely
important.
[0003] One of the early methods of removing residual matter
resulting from an angioplasty procedure using a balloon catheter
involved maintaining the balloon in an inflated state while
performing the intended intervention on the blood vessel. In this
manner, much of the material could be removed without an extraneous
filtering device. However, the reliability of such a procedure,
especially for blood vessels supplying oxygen to the brain,
necessitated substantial improvement.
[0004] Previous attempts at vascular filters have included a vena
caval filter, which is permanently deployed in the vena cava via a
peripheral vein in order to prevent embolisation of blood clots
from the veins of the legs to the lungs, thus avoiding potentially
serious and life threatening pulmonary embolism. The filter
typically included a plurality of anchoring legs bent outwardly to
form hooks to penetrate the vessel wall and secure the filter
permanently in position. An example of such a device is disclosed
in U.S. Pat. No. 4,619,246.
[0005] While conventional vena caval filters work well for their
intended purposes, they suffer from the disadvantages associated
with damaging the inner vessel wall through the inherent
penetrating nature of the hooks, and blockage caused over time as
the filter becomes endothelialized with the blood vessel inner wall
or as recurrent blood clots obstruct blood 5 flow through the
filter.
[0006] In an effort to resolve the problems with vena caval
filters, those skilled in the art have developed temporary
filtering mechanisms that attach to an angioplasty catheter and
withdraw from the vasculature following the procedure. One
proposal, disclosed in U.S. Pat. No. 4,723,549, discloses a
collapsible wire mesh filter disposed around the distal portion of
a wire guided balloon catheter. A filter balloon is positioned
beneath the wire mesh and inflates radially outwardly to expand the
wire mesh when inserted downstream of a stenosed blood vessel. As
the vessel is treated, fine particles dislodged from the stenosis
are trapped by the mesh and subsequently removed with the filter
and catheter following the procedure.
[0007] A similar device and method, disclosed in U.S. Pat. No.
4,873,978 includes a balloon catheter directed through a
vasculature by a guide wire. The catheter mounts a strainer at its
distal end that responds to actuation of a separate control wire to
open and close a plurality of tines capable of retaining dislodged
particles from a treated stenosis.
[0008] The temporary filter devices described above require
additional lumens and/or control wires beyond those associated with
the catheter guide wire to control the filtering procedure. The
extra lines and wires typically create added complexity for the
operator. Moreover, it is often desirable to adjust the relative
spacing between the deployed filter and the stenosed area due to
the potential presence of additional blood vessels proximate the
stenosis. Because the conventional filters are mounted to the
distal ends of the respective catheters, adjustments during the
procedure typically cannot be made. Furthermore, the use of balloon
catheters and stent devices involving the same procedure could not
be achieved with filter protection in place.
[0009] Therefore, a need exists in the art for a temporary vascular
filter which does not require additional control wires and catheter
lumens. Moreover, the need exists for such a filter in which
adjustment of the filter with respect to a lesioned vessel area,
and allows for the exchange of various types of devices (e.g.,
balloon catheters, stents, etc.), while maintaining protection
against distal emboli. The temporary vascular filter guide wire of
the present invention satisfies these needs.
SUMMARY OF THE INVENTION
[0010] The apparatus and method of the present invention minimizes
the complexity associated with manipulating a vascular filter
during an angioplasty or stent placement procedure by incorporating
the filter on a catheter guide wire such that the guide wire
performs the dual functions of guiding the catheter to a stenosed
location, and filtering dislodged particles flowing downstream of
the treated area. Moreover, because the guide wire operates
independently of the catheter, relative spacing between the filter
and the lesion location may be easily altered, and exchanges of
various devices over the wire are possible.
[0011] To realize the advantages described above, the invention, in
one form, comprises a vascular filter guide wire for directing
precision placement of a catheter or stent proximate a lesion and
selectively filtering particulate debris dislodged by treatment.
The guide wire includes an actuating mechanism and an elongated
flexible core wire having a proximal end mounted to the actuating
mechanism and a distal end for insertion through a vasculature to a
position downstream of the lesion. A tubular flexible shaft is
slidably disposed telescopically along the core wire. The shaft
includes a proximal portion affixed to the actuating mechanism in
movable relation to the wire proximal end, and a distal portion
disposed inwardly from the core wire distal end for placement
downstream of the lesion. A collapsible strainer coupled to the
shaft distal portion is operable, in response to relative
displacement between the shaft and the core wire, to radially
extend outwardly within the vasculature so that it can trap
particulate matter arising from the treatment of the lesion.
[0012] In another form, the invention comprises a catheter system
for treating a lesion within the vasculature. The catheter system
includes a catheter having a lesion treatment device and a vascular
filter guide wire for directing the catheter to the lesion. The
guide wire includes a collapsible filter for deployment downstream
of the catheter to trap particulate matter dislodged from the
lesion during the treatment.
[0013] In yet another form, the invention comprises a method of
filtering particulate debris from a vasculature caused by treatment
of a lesion with a catheter having a lesion treatment portion, the
catheter being guided to the location of the lesion by a vascular
filter guide wire having a core wire, a slidable shaft, and a
collapsible filter mounted on the shaft and deployable upon
relative displacement between the core wire and the shaft. The
method includes the steps of first guiding the vascular filter
guide wire through the vasculature along a predetermined path to a
lesion such that the filter is disposed downstream of the lesion.
The next step involves deploying the filter radially outwardly by
shifting the shaft relative to the core wire. Then, the catheter is
run over the guide wire along the predetermined path to position
the lesion treatment portion of the catheter proximate the lesion.
The method continues by treating the lesion according to a
predetermined procedure then maintaining the filter in a deployed
position until the risk of particulate matter is substantially
eliminated. The catheter is then withdrawn from the vasculature and
the filter retracted radially inwardly by shifting the shaft back
to the original position. The method then concludes with the step
of removing the guide wire from the vasculature.
[0014] One embodiment of the invention comprises a vascular filter
for controllably expanding within a blood vessel to trap
particulate matter loosened from treatment of a lesion. The filter
is responsive to relatively shiftable control elements to expand
and retract and includes a braid comprising a composite
metallic/polymeric material. The material includes a plurality of
metallic filaments mounted to the respective shiftable shaft and
core wire to define a support structure and a polymeric mesh
interwoven with the metallic filaments to define a strainer.
[0015] Another form of the invention comprises a method of
fabricating a vascular filter. The method includes the steps of
first selecting a mandrel having a plurality of consecutively
connected forms and weaving a continuous layer of braid over the
consecutively connected forms. The method proceeds by bonding the
braid filaments at spaced apart sections between respective forms
and separating the respective braided forms at the bonded sections.
The forms are then removed from the layer of braid.
[0016] Other features and advantages of the present invention will
be apparent from the following detailed description when read in
conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 is an enlarged, partial sectional view of a catheter
system of the present invention deployed within a blood vessel;
[0018] FIG. 2 is a partial longitudinal view of a guide wire in a
retracted position according to a first embodiment of the present
invention;
[0019] FIG. 3 is a partial longitudinal sectional view along line
3-3 of FIG. 2;
[0020] FIG. 4 is a partial longitudinal sectional view similar to
FIG. 3 but in a deployed orientation;
[0021] FIG. 5 is an enlarged view of detail 5-5;
[0022] FIG. 6 is a longitudinal view of a filter construction
according to an alternative embodiment of the present
invention;
[0023] FIG. 7 is a longitudinal view of a filter construction
according to yet another embodiment of the present invention;
[0024] FIG. 8 is a mandrel system for use in the method of the
present invention;
[0025] FIG. 9 is a block diagram illustrating steps in preparing
the mandrel of FIG. 8;
[0026] FIG. 10 is a block diagram illustrating steps in fabricating
the filter of the present invention;
[0027] FIG. 11a-11g are views of various stages of construction
corresponding to the steps of FIG. 10;
[0028] FIG. 12 is a partial longitudinal sectional view of a guide
wire in a retracted state according to a second embodiment of the
present invention;
[0029] FIG. 13 is a partial view of the guide wire of FIG. 12 in an
extended state;
[0030] FIG. 14 is an axial view along line 14-14 of FIG. 13;
[0031] FIG. 15 is an axial view similar to FIG. 14 and showing an
alternative strut arrangement; and
[0032] FIG. 16 is an axial view similar to FIG. 14 and showing an
alternative strut arrangement.
DETAILED DESCRIPTION OF THE INVENTION
[0033] With reference to FIG. 1, percutaneous angioplasty or stent
placement techniques enable operators to minimize trauma often
associated with more invasive surgical techniques.
[0034] This is possible through the use of a thin catheter 20 that
advances through the vascular system to a predetermined blood
vessel 22 having a lesion such as a stenosis 24 blocking the flow
of blood therethrough. Typically, the catheter includes a lesion
treatment device such as a balloon 26 or stent (not shown) for
positioning coaxially within the lesion. Once positioned, the
balloon or stent radially expands, as shown at 28, to exert a
radially outwardly directed force against the material and initiate
dilation thereof.
[0035] In order to reach the lesioned area, however, the catheter
must be able to follow a trackable path defined by a catheter guide
wire. In accordance with a first embodiment of the present
invention, a catheter guide wire, generally designated 30, provides
a trackable path for a catheter and includes a distally disposed
collapsible filter 50 to trap particulate matter dislodged by the
catheter 20 during treatment of the stenosis.
[0036] Referring now to FIGS. 2 through 5, the guide wire 30
includes a proximal section 32 comprising a solid core wire 34
having a wave-shaped proximal end 36 (FIG. 2). A tubular shaft 38
is coaxially disposed around the core wire and includes an outer
diameter equal to the nominal size of the guide wire.
[0037] The inner diameter of the tube is sized to form a friction
fit with the core wire proximal end when slid thereover during
insertion and removal of the guide wire. The shaft functions to
deploy and retract the filter device, and to guide and support the
catheter 20, and to smoothly transmit rotation from the proximal
section 32 to an intermediate section 40. Preferably, the shaft
comprises a polyimide tube or hypotube. In some applications, where
relatively long lengths are required, an extension (not shown) may
be attached to the proximal section to increase the length up to
three meters.
[0038] The intermediate section 40 extends axially from the
proximal section 32 and generally comprises an extension of the
shaft 38 to coaxially surround the core wire 34. The core wire is
formed distally with a primary tapered portion 42 defining an
annular shoulder 44 for mounting a coiled spring 46.
[0039] With further reference to FIGS. 2 through 5, the filter 50
comprises a braided basket 52 having respective inner and outer
braid layers 54 and 56 (FIG. 5) that, in one embodiment, serve as
supports for a fine filter mesh 58. The supports expand the basket
radially outwardly with the filter axial ends compressed inwardly,
and radially retract the basket with the ends tensioned outwardly.
The fine mesh 58 (FIG. 5) is interposed between the inner and outer
supports along a distal-half portion 60 of the basket to prevent
particulate matter from flowing through the blood vessel downstream
of the treated stenosis. It is contemplated that the size of the
pores of mesh 58 may be in the range of 40 to 500 microns. The
meshed distal-half of the filter forms a collection cavity 62 for
the material such that when retracted, the material is prevented
from escaping the filter.
[0040] The proximal end of the filter basket is bonded (e.g.
adhesively or by soldering) to the shaft 38 which may be inserted
between braid layers 54 and 56.
[0041] The distal extremity 57 of basket abuts a flexible coil
spring 66 that coaxially surrounds the tip of the core wire 34. The
guide wire distal tip is tapered and terminates in a
hemispherically shaped tip 72 which is also bonded (e.g. by
soldering) to the tip. The guide wire distal tip may be preformed
into a "J" configuration (not shown) to aid in advancing the guide
wire 30 through the vasculature.
[0042] With particular reference to FIG. 6, the preferred
embodiment of filter 50 according to the present invention includes
a braid comprising a composite metallic/polymeric material,
eliminating the necessity of a separate mesh layer. In such an
embodiment, a plurality of metallic filaments 82 provide structural
support to the assembly for deploying and collapsing the filter.
Polymeric filaments 84 are located on the distal half of the braid
only, to provide a filtration cone 86. The dual materials, braided
simultaneously, provide a pic density which will result in
filtration spacing of approximately 40 to 500 microns for
filtration, at a metal to polymeric ratio of approximately 1:4.
[0043] In yet another embodiment of a filter according to the
present invention, generally designated 90 and illustrated in FIG.
7, the filtering medium is wrapped in a cylinder 92 with a closed
distal end 94 and a flared proximal end 95. Flaring of the proximal
end may be effected by applying heat and pressure to the material
thereby increasing the surface area and causing the material to bow
radially outwardly. The cylinder is formed with longitudinal pleats
(not shown) that are more flexible and collapsible than a straight
cone configuration.
[0044] Referring now to FIGS. 8 and 9, fabrication of the filter 50
may be performed in accordance with a series of process steps as
described below. Initially, a mandrel 96 (FIG. 8) with a series of
molded forms 97 and 98 is prepared by selecting a mandrel of
appropriate length, at step 100 (FIG. 9), and providing a plurality
of crimps 101 (FIG. 8) on the mandrel at intervals of approximately
two to three inches, at step 102. The process proceeds by placing
molds over the crimps, at step 104, filling the molds with a
dissolvable compound, at step 106, curing the compound, at step
108, and removing the molds, at step 110. Suitable materials for
molding include water soluble plastics such as polyethylene oxide,
chemical soluble plastics such as styrene or PVC, and other water
soluble materials such as sugar cubes, or gypsum based compounds.
Molded forms may be continuously fabricated along the length of the
crimped mandrel sections to maximize production efficiency. Another
suitable method envisioned is to individually form the molds and
bond to straight mandrels.
[0045] Referring now to FIGS. 10 and 11a-g, following preparation
of the mandrel 96, the mandrel itself is selected for the method of
fabricating the filters, at step 112. The method progresses by
selecting a braider, at step 114, and braiding the inner layer 54
(FIG. 11a), at step 116, over the mandrel form system. Because of
the convenient serially connected system of forms on the mandrel,
the braider progressively weaves a continuous layer of braid over
the consecutively connected forms. After the braid is applied, the
mandrel is removed from the braider, at step 118, so that a curable
epoxy may be applied to define an adhesive joint 119 (FIG. 11b)
along spaced apart sections of the braid between forms. This step
bonds braid filaments together, at step 120, so that subsequent
separation of the forms minimizes deformation of the braid.
[0046] A center section 121 (FIG. 11c) of each braid is then cut,
at step 122, and a prefabricated filter 123 (FIG. 11d) installed
over one side of each form, at step 124. The individual segments
are then reconnected, at step 126, by splicing a section of heat
shrink tubing 127 (FIG. 11e) over each severed joint.
[0047] After the segments are re-connected, the mandrel assembly is
then re-installed into the braider for braiding of the outer basket
56 (FIG. 11f), at step 128. Following braiding, the mandrel is
removed from the braider, at step 130, with the braid filaments
bonded together to form a joint 131 (FIG. 11g), at step 132. The
mandrel is then cut at approximately one millimeter on the outside
end of the adhesive, at step 134. At this point, the molded form
may be dissolved by an appropriate solvent, at step 136, and the
mandrel removed, at step 138. Lastly, a polyimide sleeve is bonded,
at step 140, to the end opposite the filter.
[0048] The alternative filter embodiment 80 may be fabricated
similar to the procedure above with only minor variations.
Conveniently, because of the composite nature and relatively high
pic density of the metallic/polymeric braid, only one braiding step
is required. After the final braid, the polymeric strands at the
proximal end are mechanically or thermally cut away, and the
filaments fused at the large diameter of the formed cone to form
the collection cavity and to allow for greater blood flow.
[0049] In operation, the guide wire 30 may be advanced through a
vascular system in any conventional manner to establish a path for
the catheter to track over. Generally, as shown in FIG. 1, the
guide wire is inserted through the lesion and disposed downstream
of the lesion 24 a variably selected distance. The distance
selected by the operator may be conveniently adjusted merely by
further advancing or slightly withdrawing the guide wire. This
provides the highly desirable capability of enabling the operator
to independently adjust the selected distance to preclude the
possibility of embolic material progressing through a branch path
between the lesion and the filter. The catheter 20 is then inserted
along the guide wire to access the treatment area. Typically, image
scanning techniques aid in the exact positioning of the catheter
relative to the lesion such that the lesion treatment device will
have maximum effectiveness.
[0050] The filter may then be deployed by actuating an actuating
mechanism (not shown) coupled to the core wire 34 for axially
moving the shaft 38 relative to the core wire. As the shaft
advances axially along the core wire in the distal direction, the
filter basket 52, having its distal end 57 attached to the fixed
core wire and its proximal end connected to the shaft, compresses
axially and expands radially outwardly against the inner walls of
the blood vessel. In its expanded state, the filter 50 collects any
plaque that may have loosened and become dislodged from the treated
area.
[0051] Once the treatment concludes, and the catheter is withdrawn
from the body, the filter is retracted radially inwardly by
shifting the shaft back to its original position. As the filter
retracts, the collection cavity 62 traps any material strained
against the filter layer. The guide wire itself is then carefully
withdrawn from the vasculature.
[0052] Referring now to FIGS. 12 through 16, a temporary filter
guide wire according to a further embodiment of the present
invention is shown, and generally designated 200. The guide wire
generally includes a proximal end 202 having an actuating mechanism
208, an intermediate portion 220 including a housed collapsible
filter element 222, and a flexible distal end 240.
[0053] With particular reference to FIG. 12, the proximal end 202
includes a solid stainless steel core wire 204 having a diameter,
for example, of approximately 0.0075 inches and slidably confined
coaxially by an elongated shaft 206. The shaft may include, for
example, an inner diameter of approximately 0.010 inches and an
outer diameter of approximately 0.014 inches. The proximal tip of
the core wire nests within the handle mechanism 208 that includes a
rotatable handle element 209 having a formed central blind bore 210
and a threaded hollow shank 212. A fixed threaded base 214 having a
throughbore 216 receives the proximal portion of the shaft 206 and
rotatably engages the handle element to define the actuating
mechanism.
[0054] Referring now to FIGS. 12 and 13, the core wire 204 and the
shaft 206 extend longitudinally to define the intermediate portion
220 of the guide wire. The filter element 222 is mounted to the
intermediate portion and includes an intermediate quad filar spring
224 of approximately 0.002 inch diameter wire that extends
approximately three to seven centimeters from the end of the shaft,
depending on the application. The respective ends of four wires
comprising the quad spring are unwound, straightened, and outwardly
biased approximately forty-five degrees from the spring axis at
spaced apart radial locations to define a plurality of umbrella
shaped filter struts 226. These struts form the support structure
for the filter. As shown in FIGS. 14, 15, and 16, the strut spacing
may conveniently take on a variety of configurations depending on
the particular application desired. Lashed to the struts is a fine
wire mesh 228 of approximately 0.001 inches think within 40 to 500
micron pores for straining particulate matter from the
bloodstream.
[0055] Further referring to FIG. 12, the radial exterior of the
distal portion of the core wire 204 carries a bonded housing or pod
230 having an axially open mouth 232 slightly larger in diameter
than the diameter of the filter in a closed configuration. The
mouth opens into a cavity sufficiently sized to fully enclose the
filter during insertion or withdrawal of the guide wire. The pod
would also have a rounded inward edge at its proximal opening so as
to envelop the filter when retracted and prevent unintentional
engagement of a stent or catheter upon withdrawal. The pod may be
fabricated out of a spring material wound in the opposing direction
as the spiral struts to improve the sliding of the two surfaces.
Other options include a lubricious plastic such as
polyethylene.
[0056] The distal end 240 of the guide wire 200 comprises an
extension of the core wire 204 from a bonded distal joint and
surrounded by a distal spring member 242 that bonds to and projects
outwardly from the distal side of the filter housing 230. The
distal end terminates in a tip 244 that typically takes on a
pre-formed "J" shape (not shown) for steering purposes through the
vascular system.
[0057] Operation of the second embodiment proceeds in much the same
way as that of the first embodiment, with the guide wire 200 first
directed through the vasculature, followed by tracking with a
treating catheter. Like the first embodiment, the guide wire 200 is
advantageously adjustable in the blood vessel independent of the
catheter, allowing a variable selected distance between the
location of the stenosis and the filter.
[0058] However, the way in which the filter 222 expands and
retracts differs somewhat from the previously described
embodiment.
[0059] With the handle mechanism 208 in a normally open
configuration, the operator turns the rotatable element 209 to
incrementally drive the core wire 104 axially with respect to the
shaft 206. The relative axial displacement of the core wire causes
the filter housing 230 to become disengaged from the filter struts
226. Because of the spring biased nature of the filter struts 226,
as the filter exits the housing, the struts expand radially
outwardly against the blood vessel wall such that the wire mesh
spans the vessel diameter. In its extended state, the filter allows
bloodflow to continue through the vessel while dislodged material
becomes entrapped in the wire mesh for collection in the
cavity.
[0060] Once the lesion treatment procedure is complete, and the
necessity for filtering has completely diminished, the handle
mechanism is actuated to pull the core wire back to its original
position. This activity causes the housing mouth to re-engage the
filter struts and urge the struts radially inwardly as the housing
encloses the filter. With the filter fully retracted, the
streamlined guide wire may be easily and safely withdrawn from the
body.
[0061] Those skilled in the art will appreciate the many benefits
and advantages afforded the present invention. Of relative
importance is the feature that avoids any additional control wires,
beyond the guide wire itself, in order to expand and retract the
filter. Not only does this minimize the number of components
necessary to practice the invention, but the angioplasty procedure
itself is made safer for the patient.
[0062] Additionally, the present invention provides the capability
of adjusting the distance between the filter and the catheter
lesion treatment device in vivo, eliminating the need to withdraw
the guide wire or catheter for distance adjustment should the
relative spacing be inadequate.
[0063] The filter itself, in one embodiment, provides substantial
manufacturability benefits by requiring only a single braiding
step. Consequently, braiding additional filter layers adding to the
device's complexity are eliminated. By minimizing the process steps
required to fabricate the filter, costs involved in manufacture are
greatly reduced.
[0064] Moreover, the method of fabricating filters according a to
the present invention offers added efficiencies in manufacture due
to the production line processing scheme.
[0065] Employing such a scheme serves to dramatically improve the
throughput rate of filters to minimize overall costs.
[0066] While the invention has been particularly shown and
described with reference to the preferred embodiments thereof, it
will be understood by those skilled in the art that various changes
in form and detail may be made therein without departing from the
spirit and scope of the invention.
[0067] For example, the invention may be used in any intravascular
treatment utilizing a guide wire where the possibility of loosening
emboli may occur. Although the description herein illustrates
angioplasty and stent placement procedures as significant
applications, it should be understood that the present invention is
in no way limited only to those environments.
* * * * *